International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The article, been a continuation of previous studies, proposes and analyzes one of the ways to increase the efficiency of multichannel communication systems through the simultaneous use of several derivative systems of Walsh functions with different generating functions, which are necessary for constructing pseudo-random sequences (PSR). These sequences, in turn, are used as spreading codes when generating noise-like signals in multi-channel data transmission systems with channel separation (SDMA) according to the signal shape or code. The correlation properties of the PSR are studied and it is shown that, in the contrast of the known ones, the proposed approach makes it possible to increase the number of channels in the system without increasing the channel bandwidth that improves the efficiency of a multi-channel communication system.

The article presents the results of researches that are a continuation of analyzes of the correlation properties of generating functions intended for the formation of derivatives of Walsh functions. The derivatives of the Walsh functions are designed to obtain pseudorandom sequences (PRS) used in the formation of noise-like signals in multichannel data transmission systems with channel division according to the shape (code) of the signal. The analysis performed showed that the correlation properties of the derivatives of the Walsh functions depend on the type of generating functions, which were the modified Barker codes – direct and inverse composite Barker codes and de Bruijn sequences. It was justified the advantage of using these signals in the development of CDMA systems in order to reduce the interference level of multiple access and to protect against unauthorized access.

The article presents a continuation of researches in the field of improvement of signal quality in data transmission systems with code division multiple access (CDMA). It is discussed the correlation properties of pseudo-random sequences (PRS) used in the formation of noise-like signals in CDMA systems. The analysis, carried out in MATLAB environment, showed that correlation properties of the Walsh functions derivatives, used for generating PRS, have much better correlation characteristics than the original Walsh functions. Besides, these properties depend on the type of generating function of Walsh functions derivatives. It was justified the advantage of using these signals in the development of CDMA systems in order to improve the signal quality.

The article discusses the correlation properties of pseudo-random sequences (PRS) used in the formation of noise-like signals in code division coupled communication systems. The direct and inverse composite Walsh functions are considered. Comparative analysis of the correlation properties of the PRS is carried out in the Matlab medium. It is shown that the correlation properties of certain ensembles of composite Walsh functions are independent of the time shift. The possibility of using these signals in the development of systems with channels code separation in order to reduce the level of interference of multiple access is justified. Directions for further research have been determined.